Percussive tool



Feb l5, 1949- J. c. cuRTlsE-rAL PERCUSS IVE TOOL 4 Sheve-tS-She'et 1 Filed Feb. 13, 1945 Feb. 15, 1949. J. c. CURTIS' ETAL Y f 2,461,527

PERcUssIvE 'rooL n l Filed Feb. 13, 194s V4 sheets-sheet' 2 as@ Y Feb. 15,1949.

'Filed Fb. 15, 1943\ 6I, l, 132W?.

57 o/ .h/3. 9? 722 Q 5 I\\ W l "mi 76 @d Way a@ JL c. CUR-ns E-rAl.

PERcUssIvE 'roof| ,5y ,4MM MM.

4fSheets-Sheet 5 Feb. nl5, 1949 J. c. CUR-ns Erm.

PERcUssIvE T001Il Patented el. 1,57,

PERCUSSIVE TOOL John C. Curtis and Elmer G. Gartin, vCl aremont,

N. H., assignorsto Joy Manufacturing Company, a corporation of Pennsylvania Application February 13, 1943, Serial No. 475,782 l This invention relates to percussive tools and. more particularly to improvements in rock drills of the reciprocating piston, hammer type.

'An object of the present invention is to provide an improved percussive tool.V Another object is to provide an improved hammer rock drill having an improved pressure fluid motor for`v percussively actuating the drill steel. A further Yet another object is to provide an improved 9 claims.'

view showing a modified form of the construction.

rotation mechanism for the drill steel of a hammer rock drill. Yet a further object is to provide improved fluid cushioning means for the hammer -v .piston of the motor of a hammer rock drill.-. A still further object is to provide an improved chuck structure for a hammer rock drill. Still another object is to provide an improved hammer motor having improved means for transmitting the hammer blows to the shank of the drill st'el.

A further object is to provide an improved rock drill of an extremely compact design. Still another lobject is to provide an improved hammer piston structure for a hammer rock drill.

however, hereinafter more fully appear.

In the accompanying drawings there are shown Other objects and advantages of the invention will,

for purposes of illustration several formsiar'id modifications which the invention may assume in practice.

In these drawings;

Fig. 1 is a somewhat diagrammatic view in central longitudinal vertical section through-a rock drill constructed in accordance with a preferred illustrative embodiment of the invention.

Fig. 2 isa sectional view similar to Fig. 1, showing the hammer piston and iiuid distributing valves in a different position. i

Fig. Sis a cross sectional view taken on line 3-3 vof Fig. 1. Fig. 4 is a cross sectional view taken on line -Li of Fig. 1.

Fig. 5 is a side elevational view of the improved .if

hammer piston.

' Fig. 6 is an end elevational view of the hammer piston shown in Fig. 5.

Fig. 7 is a perspective view of the chuck bushing.

Fig. 8 isa perspective view of the piston striking button. Fig. 9 isl a cross sectional view taken on line 9-9 of Fig. 1. Fig. 10 is a cross sectional view taken on line Ill-: vof Fig. .11.

Fig. 11 is a fragmentary longitudinal sectional Fig. l2 is a fragmentary longitudinal sectional view showingV a further modified construction.

Fig. 13 is'adetail sectional view taken on line I3-I3 offFig. l2. n

Fig. 14 is 'a fragmentary sectional view, similar to Fig. l,l showing another .embodiment of the invention.

Fig. 15 is 'a sectional view, similar to Fig. 14, showing the hammer piston in a different position.

Fig. 16 is a cross sectional view taken on line Ill- I5 of lFig. 14.

Fig. 17 is av detail sectional view taken on the line I'I--lflof Fig. 14.

In the illustrative embodiment Iof the invention shown in vFigfs...l to 9 inclusive, the rock drill includes a 'motor cylinder I having a bore 2 containing a reciprocatory hammer piston 3. Attached byjlconventional side rods 4, 4 extending longitudinally along the opposite sides of the cylinder, to r,theopposite ends of the cylinder, is a relativelvshort front chuck housing 5 and a rear head -blo'ck 6. The hammer piston is of substantially the same external diameter vthroughout its length and has a rear piston head 'l' slidingly fittingthe cylinder zbore. The pist-on head periphery is annularly grooved at 8. Formed on the piston exterior in advance of the piston head are longitudinal flutes or grooves 9 which are slidingly interlocked `with straight keys IU formed in a sleevelike chuck nut II. The piston flutes 9 extend longitudinally on the exterior periphery of the hammer piston intermediate the extreme end pressurerareas of the piston, and extend in advance ofthe impact surface on the piston which strikes against the shank I2 of a conventional collaredl drill steel I3, as will' later be explained in' detail.

The chucknuthas a tight press fit with a bore I4 in a chuck sleeve I5 rotatably mounted in an enlarged bore'IS in theforward portion of the motorfcylinder and in alined stepped bores IIl projections between the piston flutes slidingly engaging the sleeve interior. The outer surfaces of the projections between the utes lie Vin a. circle of the same diameter as `the piston head,

rock drill above described will now be given. When the parts are in the position shown in Fig. 1, fluid under pressure may flow from the interior of the throttle valve 60 through port 62 and passage 53 to the valve chamber 45; Fluid may flow from the valve chamber past the rear face of the rear valve 46 and through supply passages 49 to the front end of the cylinder bore 2 in advance of the piston head 1 and also through passages 50, 50 between thekeys of the chuck nut to the chuck sleeve bore 2| in advance of the front end of the hammer piston. Pressure fluid acts on the effective front pressure area of the piston to move the latter rearwardly to effect its return stroke. As the hammer piston moves rearwardly the piston head face rst overruns the exhaust groove 5| and thereafter the groove 8 on the piston head connects the throwing passage 52 to the exhaust groove. Upon continued rearward piston movement the rear edge of the piston head overruns the throwing passage 52 so that pressure fluid may flow from the forward end of the cylinder bore through the throwing passage 52 to the bore 54 to act on the front face of the annular flange 56 of the rear valve 45 to` throw the latter rearwardly from the position shown in Fig. 1 to the closed position shown in Fig. 2. Thereafter the groove in the piston head connects the throwing passageV 53 to the exhaust groove 5| and upon continued rearward piston movement the piston head overruns the exhaustgroove 5| connecting the front end of the cylinder bore to exhaust. As the hammer piston approaches the rearward end of its travel the pressure uid trapped in the rear end of the cylinder bore is compressed and the compression pressure acts through the passages 48 on the forward face of the ange 5l of the front valve 41 to throw the latter rearwardly from the position shown in Fig. 1 to the position shown in Fig. 2. As the projection 38 on the rear cylinder head 36 enters the recess 39 in the piston, a pressure is built up to provide a cushion which prevents the piston from striking against the rear cylinder head. When the parts are in the-position shown in Fig. 2 pressure uid may flow from the valve chamber past the front face of the front valve 41 and through supply passages 48 to the rear end of the cylinder bore, the pressure fluid acting on the rear pressure area on the piston to move the latter forwardly to effect its working stroke. As the piston moves forwardly the piston head rst covers the exhaust groove and thereafter the groove 8 on the piston head connects the throwing passage 53 with the exhaust groove. Upon continued forward piston movement'the rear edge of the piston head overruns the throwing passage 53 so that fluid under pressure is admitted from the rear end of the cylinder bore through the passage 53 to the bore 55 at the rear side of the valve flange, the pressure uid acting on the rear face of the valve flange to throw the front valve 41 forwardly to its closed position shown in Fig. 1. Upon continued forward piston movement the groove 8 on the piston head connects the throwing passage 52 with the exhaust groove 5| and thereafter the piston head overruns the exhaust groove connecting the rear end of the cylinder bore to exhaust. As the hammer piston approaches the end of its forward travel, a compression pressure is built up within the chuck sleeve at the forward side of the piston, and this compression pressure is transmitted through the passages and supply passages 49 to the valve chamber at the rear side of the valve flange 56, the pressure uid acting on the rear pressure area of the valve flange to throw the rear valve 46 forwardly to the position shown in Fig. 1. When the hammer piston reaches the position shown in Fig. 1 the front face of the striking button 34 engages the drill steel shank to transmit the blow of the hammer piston to the drill steel to drive the latter forwardly. As the hammer piston nears its forward end of travel the reduced portion 22 on the piston will enter the bore 2|, if the striking buttons engagement with the end of the steel shank does not prevent, so that a cushion is provided to prevent the piston from striking against the chuck sleeve. The events above described are rapidly repeated during normal operationV of the motor.

During the forward piston stroke the rifle bar 69 1effects rotation of the pawl carrier 64 causing the pawls 65 of the pawl carrier to slip over the teeth of the ratchet ring so that the forward piston movement is free and unimpeded, thereby to enable the piston to strike a powerful blow against the drill steel shank., During the return stroke of the hammer piston the pawls of the pawl carrier engage the ratchet teeth 66 of the ratchet ring to hold the pawl carrier against rotation, thereby causing the rifle bar 69 to impart a rotary motion to the hammer piston which is transmitted through the chuck nut, chuck sleeve and chuck bushing to the drill steel. When it is desired to admit fluid under pressure through the fluid conducting tube 11 to the drill steel bore to clean out the drill hole, the throttle valve 60 may be rotated into a position to bring the port 'I8 into communication with the passage 19 which is connected through the gland plug 'l5 to the tube bore.

In the embodiment of the invention shown' in Figs. 14 to 1'? inclusive the cylinder and piston structure and the associated fluid distribution means together with the rotation mechanism for the ldrill steel are similar to those above described.

In this instance, the shank of the drill steel 05 is supported in a chuck bushing 0S threadedly secured at 91 within the bore of a chuck sleeve 98. The chuck sleeve is rotatably mounted in the bore of an elongated chuck housing 99 attached to the front end of a motor cylinder |00. Formed on the chuck bushing is a fiange |0| overlying the front end of the chuck housing to prevent access of dirt to the bearing surfaces. The motor cylinder has a bore |03 containing a reciprocable hammer piston |04, the latter being similar to that shown in Fig. 11.. The fluid distributing valve mechanism and the ports and passages controlled thereby are similar to those in Fig. 1. As in the modied constructions shown in Figs. 11 and 12, described above, the rifle bar 8| of the drill steel rotation mechanism engages a rie nut 82 secured within the hammer piston. Journaled in bores in the motor cylinder |00 and chuck housing 99 is a rotation sleeve |05 having longitudinal keys |06 engaged in the longitudinal flutes 9 on the hammer piston. Also engaged with the keys |05 on the rotation sleeve |05 are flutes |01 formed on the chuck sleeve 98. The chuck sleeve has an annularflange |08 arranged between the front end of the rotation sleeve |05 and a shoulder |09 in the chuck housing, and the chuck sleeve has a rearwardly projecting reduced portion ||0 receivable in the bore 32 in the hammer piston. Mounted in the bore of the reduced-portion ||0 is a tappet having a striking portion |2 engageable with the drill steel sagesse? @menti above described, aslfthexhammer piston l' limoves rearwardly,1it is .'rotated,4 through the frifle ibarf and: ratchet and pawl v'rnechanisimrandithe rotary motion of the piston` is transmitted through the rotationfsleeve 95; 'chuck sleeveii and -ehuck f piston moves forwardly to effect lits' Working Astrokegltlfie pawls of the' ratchet-rneohani'smrslip 'rover-the ratchet teethsothat the hammerlpston moves freely to deliver alblowl'to the Y'shank'of ,the drill steel. -Otherwise, this embodiment'ofA f'thefinvention is-'similarl to that above'described. Since this embodiment of the inventionoperates '2in a manner similarto thefpreferred embodiment, further description: of thelmodeoi Poper'ation thereof is unnecessary.

flAs=a result vof this invention, rit-Will be noted hat an improved'rock drillis provid'edvwhichlis 1eii'treln'elyf longitudinally compact-While f a frelaftively :long piston stroke -isv attained. It "illfur -therf'beevident that by the provision of. the'-` im- "iproved drill structure :lisclosed;"the"drill isinot :only rendered extremely compact; but` also risrielaftively simple in design. "It Willalso'be'evident Vthat by the provision offfthe" improved pressure 'fluid rotor extremely powerful hammerblows -H-:are' transmitted to the' drillV steel. NotV only is a felatively powerful rotation mechanismffor :the i iillsteel attained', but also relatively largewear- -ingsuriaces' for the rotatingv parts are Vprovided 'By the provision of the coasting front-annular 4piston portion and reduced bore inadvance of the `cylinder bore; improved cushioning ci the-piston :is attained. Other advantages of theinventi'on 5fWiH-fbe clearly apparent fto thoseskilled inthe rl'lL While there are in this application spseiiically 'fdescribed several forms and modifioationsrwliioh then invention mayv assuinein practice' it will be understood that theselforms and'fmodioations -of the sameare shown' ior-purposesbi' l illustra- -`tion' and that the invention maybe further modi- "flied-'and embodied in various other for-nis With- Iiout departing from its spiriti orthe scopefof'the :appended claims.

I What We c'eimlasnew andiidesiretofseonreiby i Letters Patent is:

L lJIn a permissive tool,l a fvylinderhavngea bore,f a hammerfpistonreeiproeable-'in s': :libere Hand'` having pressure s areas -fat itsI opposite* extrezes adapted robe subjected@ thelacsienfof .live pressure liid,` iiu'id distribution f meanslior controlling the distribution foilmotive Li-luidveul-,h respect to said cylindeiwbore foreiectingreoipro- 1 cation: ofsaid piston, said piston having lanfitrivpact Vsurface located vrearwardly -of'- itsl forward' -extre'mityand adapted to-'strikeagainstfan elei ment tobe percussively la'ctuaeed;fanddifieansfor `ioushioning salidf'piston only afterthe latterfas- -sumes I its position whereinl it v norniaillyydelivers a blow to the peroussively laetuazedI element,i said Eton-cushioning meansA -ir-iiliilirig` a boreatthe :forward end olf-saidcyl-inder aridy toL Whicii--bore pressure iiuid is supplied-'said forwardly! located bore lbeing of smaller' diameter Ith'an said'lylinder bore andreoeiving the forward-end of Y'said piston whereby rfluid is trapped in said-'forwardly vlocated 'here in advance of Ythe piston Vfafterthe blow-is struck.

2'." Inz a percussive tool, afoylinder'- having? a boretpiston4 reciprooable in said borepfl-ui'cf diss'tori reces.. 'fte y provide cushion do:

. mei

iotataolc `323133911.; we tool; e.-fcvlindertliavine" nl respect l"tdsa'icl e'iooation 'of-said iii-' havingvv a' Jlward` portion' 'of zer 'andelisifiyrif,r4 a' central-recess through its forward endA siffriace whereby "dfoivfaid'portionirs-annular iii'forrmarid the y'foot-iran rivali saidrecessiproviding arif'inipa'ct surface adapted toen gage an element to be `per- 35' 1 cussivelyx actua-ted,l a chuck. adapted Y to Asupport thepercussi J'unter/i element iin# `nositionlto be strook by L .1 on, said "ehuck" having a por tion thereof extended yrearwardly -to such: an `extent andlof suohexternai*diameter that 'said re- Y 'wardlimit 1'oi-tirar fi-nzneans' providingya Wall ffsiirrctns said :dei: rela-tionto the A #ef-iththe latterf'to ijrmiide for receiving the forward ibntion A f fluid tojs'aid ne .ntosiidohan'rber o1 MdT-portion# the radial dimension of da'nriularchefmhe. 'and `the"rabdialfdiinension .i 'saidfahniilari r'ward' portionvoi'said'piston tb), ing fsubstantial 'fthe same' ivhereby'theinher #and outer Walls oi Asaid forward-portion of said zpistonsare sealing -fits-for 'saidchuck and said as :second mentioned wall-"respectively, the rrearvward portion of` said secondmentionediwall so "ielat'edto the: path of piston -jtra'welrand` saidin'i- -pa'ctlsiirfacesolrelated cto the iorwjarded offthe tpiston'- that-said forwardv end enterslsad annular .spaceozfily aft he 'piston Vreachesthe position wel in which inpjact-on apereine-nt normally talzes 'place in a-fper'cussive toolpafcylindeihaving-a borel a 'hammer-#pistonre'eiprocable: ,in said bore ne and having ace'ntrall-reo'ess opening',` through an -ehd suriace 2 thereof, andv also-'having an 'impact surface ted'to strike blows onlan element to vbe*'permissive -=aci1iated', head for said cylin- A`der bore having a Vportion1projecting axiallyjnto 7o Ysaido3/"iurcl-er Yborel inspaced' relatiorrto'fthefoir- *cumierential wall of the latter, .andsrreceivablerin saidrj: fston recess when said piston approaches Eitsdimit 'ofrtravel in onedirectiomf.saidgpiston havingthe:V Wall thjereof ]bouiiding: said..`cent1tal l Trece'ss" cylindricalat "at least aV portion` thereof and of an internal diameter -substantially the same as the external diameter of said projecting Y cylinderhead portion wherebywhen said recess and projecting portion, are in longitudinally overlapping relation the portion 'ofsaid cyl1nder bore surrounding said projection and the space" within said'central recess have communication out off between them, iluid distribution means including means for supplying motive huid to said portion of said cylinder bore when such communication is cut olif, the length of said projecting portion with respect to the stroke of the piston being such that said piston moves olf of said projecting portion prior to the reaching of the limit of its opposite stroke.

5. In a percussive tool, a cylinder having a bore, a generally cylindrical piston reciprocable in said bore and adapted to deliver impact blows to a working implement, said piston being of substantially the same external dimensions throughout its length and having opposed pressure areas at its opposite ends, mechanism operated by said piston for intermittently rotating the working implement including rotation flutes extending longitudinally of the exterior surface of said piston between its opposite extremities, a chuck mechanism for the working implement including a rotatable annular chuck nut disposed coaxial with said cylinder and surrounding said piston at portions of its greatest external dimensions, said chuck nut having straight keys engaging said rotation flutes in all positions of said piston, said chuck nut being disposed wholly in advance of the rear end of said piston When the latter is in its forward position, and a rotatable sleeve to which said chuck nut is secured and having a bore in advance of said chuck nut and of the same diameter as said cylinder bore for receiving the forward portion of said piston, and fluid distribution means for supplying motive fluid to the remote ends of said bores to act on said piston-pressure-areas to effect reciprocation of said piston.

6. In a percussive tool, a cylinder having a bore, a hammer piston reciprocable in said cylinder bore and of the same external diameter at most points throughout its length and having a forwardly facing impact surface adapted to strike against an element to be percussively actuated, uid distributing means for distributing motive fluid with respect to the opposite ends of said cylinder bore for eiecting reciprocation of said piston, means providing a bore located in ad- Vance of said cylinder bore in alinement therewith and adapted to receive the forward end portion of said piston as the latter approaches its forward limit of travel, and means for suppying live pressure fluid from the front end of said cylinder bore to said last mentioned bore to act on the forward end portion of the piston to move the latter rearwardly including passages extending longitudinally along the exterior surface of said piston between said cylinder bore and said forwardly located bore, said passages at their forward ends terminating rearwardly of said forward end portion of said piston so that when said end portion is received in said forwardly located bore said passages are cut off from said last mentioned bore.

'I'. In a percussive tool, a member providing a longitudinal bore and a communicating reduced front bore, the latter having concentric inner and outer Walls and closed at its forward end, a hammer piston reciprocable in said longitudinal bore and having an impact surface adapted to 19 strike againstanelement to be percussively actuated, iluid distribution means for distributing pressure fluid with respect to said bores to effect movement of said piston, said piston also having 7.a reduced front end portion of annular cross section receivable in said reduced front bore in uid tight engagement with the concentric walls thereof, but only after the piston assumes its position wherein it normally delivers a blow to the lfpercussively actuated element, thereby to trap iiuid in said reduced bore in advance of said piston to cushion the forward piston movement after the blow is struck.

3. In a percussive tool, a rotatable member providing a longitudinal bore and a reduced front bore, the latter having concentric inner and outer walls and closed at its forward end, a hammer piston reciprocable in said longitudinal bore and having an impact surface adapted to strike against an element to bc percussively actuated, iiuid distribution means for distributing pressure fluid with respect to said bores to effect movement of said piston, means providing a sliding interlocking connection between said rotatable member and the exterior of said piston, said piston having a reduced front end portion of annular cross section inadvance of said interlocking connection and receivable in said reduced bore in fluid-tight engagement with the concentric walls thereof after, but only after, said piston assumes its position wherein it normally delivers a blow to the percussively actuated element, thereby a trap uid in said reduced bore in advance of said piston to cushion forward piston movement after the blow is struck.

9. In a percussive tool, a rotatable member provided with a bore the forward portion of which has concentric inner and outer walls and is closed at its forward end, a hammer piston reciprocable in said bore and having an impact surface adapted to strike against an element to be percussively actuated-` fluid distribution means for distributing pressure fluid with respect to said bore to effect movement of said piston, said piston having sliding interlocking connection with said rotatable member, said piston having its forward portion in advance of said connection of annular cross section and movable in fluid tight engagement with said concentric walls after, but only after, said piston assumes its position wherein it normally delivers a blow to the percussively actuated element, thereby to trap uid in the forward end of said bore in advance of said piston to cushion the forward pistonmovement after the blow has struck.

JOHN C. CURTIS. ELMER G. GARTIN.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 9" l284,173 Brazeiie sept. 4, 1883 351,657 Schoed Oct. 26, 1886 432,679 Sharpneck July 22, 1890 439,162 Laun Oct. 28, 1890 700,081 Phillips May 13, 1902 scarso Mitchell Apr. '1, 190s 902,836 Ross Nov. 3, 1908 915,893 Scott Mar. 23, 1909 1,029,082 Pickles June 11, 1912 (Other references on following page) Certificate of Correction Patent No. 2,461,527 February 15, 1949 v JOHN C. CURTIS ET AL. It is herebykertied that error appears in the printed specication of the above numbered patent requiring correction as follows:

Column 10, line 33, for the Words a trap read to trap;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oce.

Signed and sealed this 27th day of December, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

